Storage stable translucent flammable article

ABSTRACT

A flammable article comprising one or more polyamide gellants selected from the group consisting of fatty polyamides and ester terminated polyamides, a fatty acid ester having a carbon chain of at least 9 carbons, and a fatty acid solubilizer comprising at least 1% by weight of the flammable article.

TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to translucent flammable articles,preferably candles, which are self-supporting and storage stable.

BACKGROUND OF THE INVENTION

[0002] Compositions used to make translucent candles have traditionallypossessed one or more undesirable characteristics. Most translucentcandles do not possess enough rigidity to form a self-supporting candleand need to be housed in some type of supporting container or requiresome other type of external support. These translucent candles alsotypically lack hardness, which may lead to a malleable, gelatinousfeeling. Some of the most common drawbacks of translucent candles arethe phenomena of sweating and syneresis. Sweating is the process wherebyoils migrate out of the candle body to the surface, giving it an oilytexture, and is most commonly caused by syneresis. Syneresis occurswhenever oil is physically squeezed out from the candle body because ofexcessive chemical cross linking. The phenomena of sweating andsyneresis also contribute to the oily feeling possessed by many of thetranslucent candle compositions. Syneresis and sweating are highlyundesirable qualities in a candle because, among other reasons, 1)consumers don't want to touch a wet, oily candle; 2) the candle becomesmore brittle as oil escapes; and 3) the droplets of liquidsolvent/additives tend to burn quite quickly once the candle is lit,giving the candle a torch-like quality.

[0003] The undesirable characteristics of many translucent candlecompositions may also manifest themselves during the burning process.Some compositions used for translucent candles do not burn in anaesthetically desirable manner; these compositions may darken or produceblack smoke when burning. Other compositions used for translucentcandles may not maintain their structural integrity; these compositionsmay exhibit external cracking or internal fractures while burning. Stillother translucent compositions may exhibit undesirable characteristicsduring the manufacturing process in the form of cracking or fracturingof the composition. Those translucent candle compositions that lackstructural integrity usually are not storage stable, i.e. cannot bestored for long periods of time without the composition exhibiting somestructural deterioration. Most commonly this structural deteriorationoccurs in the form of sweating or syneresis.

[0004] U.S. Pat. No. 6,111,055 (U.S. Pat. No. 6,111,055) describes asolid composition that may be used as the base material of a translucentcandle. The composition includes an ester terminated dimer acid-basedpolyamide that may be blended with a solvent to form a gel. The geltypically lacks hardness and has an oily and gelatinous feeling. Thus, asolid coating is also disclosed in U.S. Pat. No. 6,111,055 to providemechanical stability and to eliminate the oily feel of the surface ofthe gel. The gel disclosed in U.S. Pat. No. 6,111,055 noticeably acceptsfingerprints and is easily marred when touched. The candle compositionof U.S. Pat. No. 6,111,055 also exhibits syneresis and sweating; thesolid coating helps to reduce, but does not eliminate, this syneresis.Furthermore, the translucent candle compositions described in U.S. Pat.No. 6,111,055 are not storage stable. i.e., they do not maintain theirstructural or aesthetic integrity over long periods of time such as whenthey are stored. Over long periods of time such as during storage thetranslucent candle composition disclosed in U.S. Pat. No. 6,111,055 willexhibit sweating and syneresis.

[0005] U.S. Pat. No. 6,054,517 (U.S. Pat. No. 6,054,517) describes aclear solid composition that may be used as the base material of atranslucent candle. The composition includes one or more polyamideresins present in a total amount of about 60 to 80% by weight of thecomposition, one or more solubilizers, and one or more emulsifiers. Thecomposition described in U.S. Pat. No. 6,054,517 is self-supporting anddoes not have a gelatinous feeling. The composition described in U.S.Pat. No. 6,054,517 also is described as burning without cracking orfracturing. However, the candle compositions described in U.S. Pat. No.6,054,517 are not storage stable, i.e. they do not exhibit stability ormaintain their structural or aesthetic integrity over long periods oftime such as when they are stored. Specifically, the composition of U.S.Pat. No. 6,054,517 will exhibit sweating and syneresis over long periodsof time.

[0006] Thus, it would be desirable to have a translucent candlecomposition that was self-supporting, maintained its structuralintegrity while burning, burned cleanly, the surface of which was notoily to the touch or easily impressed by fingertips, and furthermore wasstorage stable.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to a flammable articlecomprising one or more polyamide gellants selected from the groupconsisting of fatty polyamides and ester terminated polyamides, one ormore solvents, wherein one of the solvents is a fatty acid ester havinga carbon chain of between about 9 to about 30 carbons, and one or moresolubilizers, wherein one of the solubilizers is a fatty acid having acarbon chain of between about 1 to about 22 carbons. The solubilizercomprises at least 1% by weight of the composition. The flammablearticle is storage stable and does not require a supporting container orstructure. Preferably, the flammable article also comprises a wick andis a candle. The candle burns cleanly and evenly and is alsotranslucent, preferably transparent.

[0008] Further objects and advantages of the subject invention will beapparent to one of ordinary skill in the art or will be pointed outhereinafter.

DETAILED DESCRIPTION Definitions

[0009] As used herein “composition” refers to a base material from whichthe flammable article of the present invention can be made. Thecomposition includes a gellant, a solvent and a solubilizer, all mixedtogether. The gellant is the component that provides structure to thecomposition, however, the properties of that structure may be affectedby many factors, such as the amount of solvent used and the type andamount of other additives including oils and plasticizers. The solventbinds to the gellant and the solubilizer assists in this coupling; thecombination of the gellant, the solvent and the solubilizer provides theflammable article with many of its desirable properties, includingclarity, storage stability, and the ability to be self-supporting. Inthe preferred embodiment of a candle, the combination of the gellant,the solvent and the solubilizer provides the candle with the desirableproperties it exhibits when it is burning, such as a flame that burnscleanly, evenly and substantially, without producing excessive amountsof black smoke or darkening the candle itself. However, other factors,such as the size and type of the wick and other components included inthe composition, can also impact the burning characteristics of thecandle.

[0010] The terms “hydrocarbon” and “hydrocarbyl” as used herein describeorganic compounds or radicals consisting exclusively of the elementscarbon and hydrogen. These moieties include alkyl, alkenyl, alkynyl, andaryl moieties. These moieties also include alkyl, alkenyl, alkynyl, andaryl moieties substituted with other aliphatic or cyclic hydrocarbongroups, such as alkaryl, alkenaryl and alkynaryl. Unless otherwiseindicated, these moieties preferably comprise 1 to 20 carbon atoms.

[0011] The “substituted hydrocarbyl” moieties described herein arehydrocarbyl moieties which are substituted with at least one atom otherthan carbon, including moieties in which a carbon chain atom issubstituted with a hetero atom such as nitrogen, oxygen, silicon,phosphorous, boron, sulfur, or a halogen atom. These substituentsinclude halogen, heterocyclo, alkoxy, alkenoxy, alkynoxy, aryloxy,hydroxy, protected hydroxy, keto, acyl, acyloxy, nitro, amino, amido,nitro, cyano, thiol, ketals, acetals, esters and ethers.

[0012] Unless otherwise indicated, the alkyl groups described herein arepreferably lower alkyl containing from one to eight carbon atoms in theprincipal chain and up to 20 carbon atoms. They may be straight orbranched chain or cyclic and include methyl, ethyl, propyl, isopropyl,butyl, hexyl and the like.

[0013] Unless otherwise indicated, the alkenyl groups described hereinare preferably lower alkenyl containing from two to eight carbon atomsin the principal chain and up to 20 carbon atoms. They may be straightor branched chain or cyclic and include ethenyl, propenyl, isopropenyl,butenyl, isobutenyl, hexenyl, and the like.

[0014] Unless otherwise indicated, the alkynyl groups described hereinare preferably lower alkynyl containing from two to eight carbon atomsin the principal chain and up to 20 carbon atoms. They may be straightor branched chain and include ethynyl, propynyl, butynyl, isobutynyl,hexynyl, and the like.

[0015] The terms “aryl” or “ar” as used herein alone or as part ofanother group denote optionally substituted homocyclic aromatic groups,preferably monocyclic or bicyclic groups containing from 6 to 12 carbonsin the ring portion, such as phenyl, biphenyl, naphthyl, substitutedphenyl, substituted biphenyl or substituted naphthyl. Phenyl andsubstituted phenyl are the more preferred aryl.

[0016] The terms “halogen” or “halo” as used herein alone or as part ofanother group refer to chlorine, bromine, fluorine, and iodine.

[0017] The terms “heterocyclo” or “heterocyclic” as used herein alone oras part of another group denote optionally substituted, fully saturatedor unsaturated, monocyclic or bicyclic, aromatic or nonaromatic groupshaving at least one heteroatom in at least one ring, and preferably 5 or6 atoms in each ring. The heterocyclo group preferably has 1 or 2 oxygenatoms, 1 or 2 sulfur atoms, and/or 1 to 4 nitrogen atoms in the ring,and may be bonded to the remainder of the molecule through a carbon orheteroatom. Exemplary heterocyclo include heteroaromatics such as furyl,thienyl, pyridyl, oxazolyl, pyrrolyl, indolyl, quinolinyl, orisoquinolinyl and the like. Exemplary substituents include one or moreof the following groups: hydrocarbyl, substituted hydrocarbyl, keto,hydroxy, protected hydroxy, acyl, acyloxy, alkoxy, alkenoxy, alkynoxy,aryloxy, halogen, amido, amino, nitro, cyano, thiol, ketals, acetals,esters and ethers.

[0018] As used herein, a fatty acid is composed of a chain of alkylgroups containing from 1 to 24 carbon atoms (usually an even number) andcharacterized by a terminal carboxyl group —COOH. A fatty acid is acarboxylic acid derived from or contained in an animal or vegetable fator oil. Fatty acids may be saturated or unsaturated (also known asolefinic). A saturated fatty acid is a fatty acid in which the carbonatoms of the alkyl chain are connected by single bonds. Examples ofsaturated fatty acids include, but are not limited to, butyric (C₄),lauric (C₁₂), palmitic (C₁₆), and stearic (C₁₈). An unsaturated fattyacid is a fatty acid in which there are one or more double bonds betweenthe carbon atoms in the alkyl chain. Examples of unsaturated fatty acidsinclude, but are not limited to, oleic (C₁₈), linoleic (C₁₈), andlinolenic (C₁₈). These acids are usually vegetable derived and consistof alkyl chains containing 18 or more carbon atoms with thecharacteristic end group —COOH.

[0019] Unless otherwise indicated, a fatty acid ester is a fatty acidwith the active hydrogen of the —COOH group, the carboxylic acid,replaced by the alkyl group of a monohydric alcohol. The esterificationof a fatty acid, RCOOH, by an alcohol, R′OH, yields the fatty acid esterRCOOR′. Thus, R, the “fatty” portion of the fatty acid ester, iscomposed of a chain of alkyl groups containing from 4 to 22 carbon atomsand may be saturated or unsaturated. A saturated fatty acid ester is afatty acid ester in which the carbon atoms of R are connected by singlebonds. Examples of saturated fatty acid esters include, but are notlimited to, butyric (C₄), lauric (C₁₂), palmitic (C₁₆), and stearic(C₁₈). An unsaturated fatty acid ester is a fatty acid ester in whichthere are one or more double bonds between the carbon atoms in R.Examples of unsaturated fatty acids include, but are not limited to,oleic (C₁₈), linoleic (C₁₈), and linolenic (C₁₈).

[0020] Unless otherwise indicated, a fatty alcohol is a primary alcohol(from C₁ to C₂₄) with a straight or branched alkyl chain. The carbonchain can be saturated or unsaturated. A saturated fatty alcohol is afatty alcohol in which the carbon atoms of the alkyl chain are connectedby single bonds. Examples of saturated fatty alcohols include, but arenot limited to, octyl, decyl, lauryl, myristyl, cetyl, and stearyl. Anunsaturated fatty alcohol is a fatty alcohol in which there are one ormore double bonds between the carbon atoms in the alkyl chain. Examplesof unsaturated fatty alcohols include, but are not limited to, oleyl,linoleyl, and linolenyl.

[0021] As used herein, “R” means lower alkyl unless otherwise defined.

Composition of the Article

[0022] Surprisingly, it has been found that the qualities of storagestability, structural integrity, clean and even burning,self-supporting, and a resilient and aesthetically desirable surface canbe achieved and the limitations possessed by known translucent flammablearticles, specifically transparent candles, can be overcome through theuse of a combination of a particular type of solvent with a polyamidegellant and a particular type of plasticizer. Thus, storage stabletranslucent candles can be made by using a hydrocarbon fatty acid esterbetween about 9 to about 30 carbons as a solvent in combination with apolyamide gellant and one or more solubilizers that are fatty acids orfatty alcohols. Thus, the composition of the invention contains one ormore polyamide gellants, one or more solvents, and one or moresolubilizers. The polyamide gellants are preferably fatty polyamides,ester terminated polyamides, or a mixture thereof. The solubilizers arepreferably fatty acids having a carbon chain of between about 1 to about22 carbons or fatty alcohols having a carbon chain of between about 1 toabout 24 carbons. The composition may also optionally contain theadditional components of hydrocarbon oil, a plasticizer, fragrances andcoloring agents.

[0023] If a fatty polyamide is used as the polyamide gellant, thecomposition typically contains from about 10 to about 70 weight % fattypolyamide. Preferably, the composition contains from about 10 to about50 weight % fatty polyamide. More preferably, the composition containsfrom about 20 to about 50 weight % fatty polyamide.

[0024] If an ester terminated polyamide is used as the polyamidegellant, the composition typically contains from about 10 to about 90weight % of ester terminated fatty acid. Preferably, the compositioncontains from about 10 to about 70 weight % ester terminated polyamide.More preferably, the composition contains from about 20 to about 50weight % ester terminated polyamide.

[0025] If a mixture of the two types of polyamide gellants is employedin the composition, the composition typically contains between about 10to about 90 weight % total polyamide gellant. Preferably, when a mixtureof polyamide gellants is employed, the composition contains betweenabout 20 to about 70 weight % of total polyamide gellant. Morepreferably, when a mixture of polyamide gellants is employed thecomposition contains between about 30 to about 60 weight % of totalpolyamide gellant.

[0026] The composition also contains one or more solvents, which iseither a fatty acid ester, a hydrocarbon oil, or mixture thereof. Ifonly one solvent is employed, the solvent is preferably a fatty acidester solvent having a carbon chain of between about 9 to about 30carbons. If more than one solvent is employed in the invention, thanpreferably one of these solvents is a C9 to C30 fatty acid ester.

[0027] Irrespective of which type of solvent is used, the total amountof solvent in the composition preferably contains between about 5 toabout 70 weight % of total solvent. More preferably, the compositioncontains between about 10 to about 50 weight % fatty acid ester solvent.Still more preferably, the composition contains between about 10 toabout 20 weight % fatty acid ester solvent.

[0028] If only a fatty acid ester is employed as the solvent in theinvention, the amount of fatty acid ester in the composition istypically between about 5 to about 70 weight % of total solvent.Preferably, the amount of fatty acid ester in the composition is betweenabout 10 to about 50 weight % of total solvent. More preferably, thecomposition contains between about 10 to about 20 weight % fatty acidester solvent.

[0029] A hydrocarbon oil may also be included in the composition as asolvent. When employed as a solvent in the invention, the hydrocarbonoil preferably comprises up to about 50% by weight of the composition.When included, the hydrocarbon oil more preferably comprises about 10%to 406% by weight of the composition. When included, the hydrocarbon oileven more preferably comprises between about 15% to 30% by weight of thecomposition.

[0030] The composition also contains a solubilizer, which is preferablyeither a fatty acid, a fatty alcohol or combination thereof. Thecomposition preferably contains at least 1% solubilizer by weight. Thesolubilizer functions to improve the solubility of the polyamide gellantin the solvent, enhancing the coupling of the polyamide gellant to thesolvent. This coupling assists in providing the structural integrity,clarity, storage stability and absence of sweating and syneresisproperties characteristic of flammable articles and candles made withthe composition of the present invention. The composition typicallycontains from between about 1 to about 75 weight % of solubilizer. Thecomposition preferably contains between about 2 to 30% solubilizer byweight, more preferably about 3-10% solubilizer by weight, and even morepreferably 5-7% solubilizer by weight.

[0031] The composition may also contain a plasticizer. When used in thecomposition, the plasticizer preferably comprises between about 0% toabout 15% by weight of the composition. More preferably, the plasticizercomprises about 7% to 12% by weight of the composition.

[0032] One or more fragrances may also be included in the composition.The total amount of such fragrances in the composition is preferablybetween about 0-5%, more preferably between about 1-4%, and even morepreferably between about 2-3%.

[0033] The composition may also include one or more coloring agents. Thetotal amount of such coloring agents in the composition is typicallybetween about 0-5%, preferably between about 1-4%, and more preferablybetween about 2-3%.

[0034] A preferred embodiment of the flammable article is a translucentcandle. The translucent candles are characterized in that they arestorage stable, i.e., the candles maintain their structural andaesthetic integrity when stored for significant periods of time.Furthermore, the translucent candles are self-supporting in that they donot require a container or external support, and are capable of burningwithout such a support. The translucent candles do not produce excessiveamounts of black smoke or darken during burning. Additionally, thetranslucent candles are easily handled and do not require a coating. Thesurface of the candles is preferably not oily or greasy to the touch,nor is the surface easily marred by fingerprints when the candle isbeing handled. Rather, the surface of the candles is resilient to thetouch and is not easily marred when handled. Thus, candles of thepresent invention do not require a coating, as do many of thetranslucent candles of the prior art, for structural support oraesthetic reasons.

[0035] A translucent, free-standing and storage stable flammable articlemay be prepared, for example, using a C₁-C₂₂ fatty acid solubilizer incombination with a polyamide gellant and a solvent. In general, thesolubilizers facilitate exceptional coupling between the polyamidegellant and solvent. This coupling is believed to assist in providingthe structural integrity, clarity, absence of sweating and syneresis andstorage stability properties characteristic of flammable articles andcandles made with the composition of the present invention. Withoutbeing limited to any particular theory, it is presently believed thatthe coupling between the solvent and polyamide gellant and solubilizeris due to physical bonding between various portions of these componentsin the form of hydrogen bonding, dipole-dipole interactions, Van DerWaals interactions and related forces.

Components of the Composition Solubilizer

[0036] The composition of the invention contains one or moresolubilizers. Solubilization is a phenomenon that enables the formationof a solution. It is related to the presence of amphiphiles, moleculespossessing the dual properties of being both polar and non-polar, in thesolution that have the ability to increase the solubility of materialsthat are normally insoluble or only slightly soluble, in the dispersionmedium. Solubilizers often have surfactant properties. Their functionmay be to enhance the solubility of a solute in a solution, rather thanacting as a solvent, although in exceptional circumstances, a singlecompound may have both solubilizing and solvent characteristics. Thesolubilizers useful in the present invention improve the solubility ofthe polyamide gellant in the solvent. In enhancing the solubility of thepolyamide gellant in the solvent, the solubilizer improves the clarityof the gellant/solvent blend. It is believed that the solubilizers alsofunction as a coupling agent, coupling components in the solution andproviding the solution with order and stability through physicalinteractions. These physical interactions can be hydrogen bonding,polar-polar interactions, Van Der Waals interactions and related forces.

[0037] Two types of solubilizers are preferred for use with the presentinvention, fatty acids and fatty alcohols. The hydrocarbon chains of thefatty acid and fatty alcohol can be linear, branched or cyclic andsaturated or unsaturated. Solubilizers possessing a branched carbonchain are preferred for use in the invention. The carbon chain of thefatty acids and fatty alcohols is preferably branched in the form of anisopropyl group at the end opposite the carboxylic acid or alcoholfunctionality. An example of such a carbon chain is isodioctyl. Both thefatty acid ester and fatty alcohol are preferably monofunctional; thefatty acid ester is preferably a monofunctional ester (i.e. possessing asingle ester moiety) and the fatty alcohol is preferably amonofunctional alcohol (i.e. possessing a single alcohol moiety).

[0038] Be it fatty acid or fatty alcohol, the solubilizer used in thepresent invention is preferably a liquid at room temperature. The carbonchain of either the fatty acid or the fatty alcohol is preferably notthat long; if the number of carbons in the carbon chain is too high, thesolubilizer becomes solid and negatively impacts the clarity of thecomposition, by causing turbidity. Thus, the carbon chain of the fattyalcohol is preferably between about 1 to about 24 carbons. Morepreferably, the carbon chain of the fatty alcohol is between about 10 to20 carbons. Still more carbon atoms. Isostearic alcohol is an example ofa preferred fatty alcohol.

[0039] The carbon chain of the fatty acid is preferably between about 1to about 22 carbons. Examples include caproic acid, caprylic acid,capric acid, lauric acid, myristic acid, palmitic acid, palmitoleicacid, stearic acid, and isostearic acid. More preferably, the carbonchain of the fatty acid is between about 10 to 20 carbons. Even morepreferably, the carbon chain is between about 14 to about 18 carbonatoms. Isostearic acid is an example of a preferred fatty acid.Isostearic acid is a preferred solubilizer for use in the invention dueto its compatibility with many of the other components in thecomposition. When isostearic acid is used as the only solubilizer in thecomposition, the isostearic acid is typically present in the compositionin a total amount of about 1 to 75% by weight, preferably in an amountof about 2 to 30% by weight, more preferably in an amount of about 3-10%by weight, and even more preferably in an amount of about 5-7% byweight.

[0040] A mixture of solubilizers may also be used in the invention;preferably, isostearic acid is present in this mixture. Thus, a mixtureof isostearic acid with another solubilizer, either another fattyalcohol or fatty acid, may be used. A preferred mixture is a mixture ofisostearic acid and isostearic alcohol. When a mixture of solubilizersis employed, the total amount of solubilizer in the composition istypically between about 1 to about 75% by weight. Preferably, the amountof total solubilizer present in the composition is between about 2 to30% by weight, more preferably about 3-10% by weight, and even morepreferably 5-7% by weight.

[0041] In a mixture of solubilizers, isostearic acid is preferablypresent in a weight ratio of between about 6.5:10 to about 10:10, i.e.,6.5 parts isostearic acid to 10 parts total solubilizer to about 10parts isostearic acid to 10 parts total solubilizer. More preferably,isostearic acid is present in a mixture of solubilizers in a weightratio of between about 9.5:10 to about 10:10, i.e., 9.5 parts isostearicacid to 10 parts total solubilizer to about 10 parts isostearic acid to10 parts total solubilizer.

Gellant

[0042] The gellants employed in the composition of the present inventionare preferably polyamide gellants. Polyamides are polymers that containrecurring amide groups as integral parts of the main polymer chains. Ifthe polymers are formed by the condensation of diamines and dibasicacids, they are called AABB types, and can be represented by the generalformula H₂NRNH(COR′CONHRNH)_(n)COR′COOR″, where R and R′ are C1-C18, andR″ is either H or C1-C18. If a secondary diamine is used, the generalformula above can be N-substituted with an R group. A common form ofshorthand symbolism that serves to identify aliphatic polyamides is theuse of numbers that signify the number of carbon atoms in the respectivemonomers. For AABB polymers, two numbers are used; the first gives thenumber of carbon atoms separating the nitrogen atoms of the diamines,and the second gives the number of straight-chain carbon atoms in thedibasic acids. For example, nylon-6,6 is prepared from hexamethylenediamine and adipic acid.

[0043] Polyamides prepared by the self-condensation of an amino acid arecalled type AB, with the general formula H₂NRCO(NHRCO)_(n)NHRCOOR′,where R is an aliphatic carbon chain of any number of carbon atoms, andR′ can be R or H. This type of polyamide also uses a number system toidentify the composition, but only a single number signifying the numberof carbon atoms in the amino acid monomers is used. For example, nylon-6is polycaprolactam, and nylon-12 is polylauryllactam.

[0044] Two classes of polyamide gellants are preferred for use in theinvention. The first class of polyamide gellant is based on vegetablefatty acids and polyamines such as the Versamid® series from Henkelcorporation, or the UniRez® series from Arizona Chemical. This class ofpolyamides is based on the condensation of (1) diamines with (2)relatively high molecular weight polybasic acids or esters, includingdibasic acids or esters, which are obtained from thermal polymerizationof a diene acid or ester, such as linoleic acid (for example, linoleatesfrom soy bean, cotton seed or corn oils). The dibasic or polybasic acidsare normally mixtures of materials. Typically, the largest component isa dibasic dimeric fatty acid possessing 18 carbon atoms per carboxylgroup, but other mono- or polybasic fractions may be present. Thesemono- or polybasic acids may be a product of the polymerization ofunsaturated vegetable oil acids or esters, or they can be deliberatelyadded to the dimer acids, to modify the nature of the resulting polymer.The physical properties of polyamides of this type are determined to alarge extent by the identity of the dimer acids used in theirproduction. These polyamides are also called fatty polyamides, orpolyamides from long-chain fatty acids (and esters). These polyamideshave greater solubility in selected solvents and lower crystallinitythan simpler nylons such as, for example, nylon-6,6 or nylon-6.

[0045] Examples of commercial polyamides which can be used as thepolyamide gelling agent in the composition of the present invention areVersamid 1655® (by Henkel Corporation, CAS #68915-56-0). Othercommercial polyamides which can be used as the polyamide gelling agentinclude Uni-Rez 2620®, Uni-Rez 2626®, and Uni-Rez 2970®. The Uni-Rez®polyamides are by Union Camp Corporation, and the Versamid® polyamidesare by Henkel Corporation.

[0046] Versamid 1655® is prepared from dimers of C₁₈ unsaturated fattyacids which are partially hydrogenated, azelaic acid (nonanedioic acid),ethylene diamine, hexamethylene diamine and stearic acid. Versamid 744®is prepared from dimers of C₁₈ unsaturated fatty acids, ethylenediamine, hexamethylene diamine and propionic acid. Uni-Rez 2931® isprepared from dimers of C₁₈ unsaturated fatty acids, ethylene diamineand tall oil fatty acids. Versamid 930® is prepared from adipic acid andhexylenediamine.

[0047] The second type of polyamide gellant is based on complex fattyacids that are terminated by esters such as the UniClear® series fromArizona Chemical company. Such a gellant is referred to as anester-terminated polyamide (ETPA) and comprises molecules of the formula(1):

[0048] wherein n designates a number of repeating units such that estergroups constitute from 10% to 50% of the total of the ester and amidegroups; R¹ at each occurrence is independently selected from an alkyl oralkenyl group containing at least 1 carbon atom, preferably at least 4carbon atoms; R² at each occurrence is independently selected from aC₄-₄₂ hydrocarbon group with the proviso that at least 50% of the R²groups have 30-42 carbon atoms; R³ at each occurrence is independentlyselected from an organic group containing at least two carbon atoms inaddition to hydrogen atoms, and optionally containing one or more oxygenand nitrogen atoms; and R^(3a) at each occurrence is independentlyselected from hydrogen, C₁₋₁₀ alkyl and a direct bond to R³ or anotherR^(3a) such that the N atom to which R³ and R^(3a) are both bonded ispart of a heterocyclic structure defined in part by R^(3a)—N—R³, suchthat at least 50% of the R^(3a) groups are hydrogen. For convenience,R¹, R², R³ etc. will be referred to herein as “groups”, however theycould equally well be referred to as radicals (R¹) and diradicals (R²and R³).

[0049] As may be seen from formula (1), the preferred ETPA gellants haveester groups, ie., —C(═O)O— groups at both ends of a series of amidegroups, i.e., —N(R^(3a))C(═O)— groups. The letter “IN” designates thenumber of repeating units present in a molecule of ETPA, and is aninteger greater than 0. N may be 1, in which case the ETPA containsequal numbers of ester and amide groups, i.e., the ester groupsconstitute 50% of the total of the ester and amide groups in the ETPAmolecule. The preferred ETPA gellants are of relatively low molecularweight, so that N is preferably 1 to about 10, and more preferably is 1to about 5. Due to the low molecular weight of the ETPA molecules, thesemolecules could also properly be called ester-terminated oligoamides.

[0050] The ester groups constitute about 10% to about 50%, preferablyabout 15% to about 40%, and more preferably about 20% to about 35% ofthe total of the ester and amide groups. The ETPA gellant of the presentinvention also includes mixtures of different ETPA molecules describedabove. Indeed, a preferred ETPA gellant includes a mixture of ETPAmolecules of formula (1) having various N values.

[0051] The R¹ group in formula (1) is an alkyl or alkenyl group whichcontains at least 1, and preferably at least 4 carbon atoms. Alkylgroups are preferred, however alkenyl groups having 1-3, and preferably1 site of unsaturation are also suitable.

[0052] It is preferred that the number of carbon atoms in the R¹ groupbe greater than 4, and preferably R¹ has at least about 10 carbon atoms,more preferably at least about 12 carbon atoms, then ETPA is anexcellent gellant for aliphatic hydrocarbon. The upper range for thenumber of carbon atoms in the R¹ group is not particularly critical,however, preferably the R¹ group has less than or equal to about 24carbon atoms, and more preferably has less than or equal to 22 carbonatoms. R¹ groups having about 16-22 carbon atoms are highly preferred.The identity of R¹ at any occurrence is independent of the identity ofR¹ at any other occurrence.

[0053] The R² group in formula (1) is suitably a hydrocarbon containing4 to 42 carbon atoms. A preferred R² group contains 30-42 carbon atoms(ie., is a C₃₀₋₄₂ group), and at least 50% of the R² groups in an ETPAgellant preferably have 30-42 carbon atoms. Such R² groups are readilyintroduced into an ETPA when the gellant is prepared from polymerizedfatty acid, also known as dimer acid. Polymerized fatty acid istypically a mixture of structures, where individual dimer acids may besaturated, unsaturated, cyclic, acyclic, etc. Thus, a detailedcharacterization of the structure of the R² groups is not readilyavailable. However, good discussions of fatty acid polymerization may befound in, e.g., U.S. Pat. No. 3,157,681 and Naval Stores—Production,Chemistry and Utilization, D. F. Zinkel and J. Russel (eds.), Pulp.Chem. Assoc. Inc., 1989, Chapter 23.

[0054] Typical unsaturated fatty acids used to form polymerized fattyacid include oleic acid, linoleic acid, linolenic acid, etc. Tall oilfatty acid, which is a mixture containing long-chain unsaturated fattyacids obtained as a byproduct of the wood pulping process, is preferredfor preparing polymerized fatty acid useful in ETPA formation. Whiletall oil fatty acid is a preferred source of long-chain fatty acid, thepolymerized fatty acid may alternatively be prepared by polymerizationof unsaturated fatty acids from other sources, e.g., soybeans or canola.The R² group containing 30-42 carbon atoms may thus be described ashaving the structure of dimer or trimer acid, after removal of thecarboxylic acid groups (as seen below, the carboxylic acid groups ofdimer acid can react to form the amide and/or ester groups of the ETPAgellant).

[0055] While the preferred ETPA gellants contain at least 50% C₃₀₋₄₂groups as the R² group, more preferably the total of the R² groupsconsist of at least 75% C₃₀₋₄₂ groups, and still more preferably consistof at least 90% C₃₀₋₄₂ groups. ETPA gellants of formula (1) wherein R²is entirely C₃₀₋₄₂ are preferred gellants of the invention.

[0056] However, ETPA gellants may also contain R² groups having lessthan 30 carbon atoms. For example, an ETPA gellant may contain one ormore R² groups having about 4 to 19, preferably about 4 to 12, and morepreferably about 4 to 8 carbon atoms. The carbon atoms may be arrangedin a linear, branched or cyclic fashion, and unsaturation may be presentbetween any two carbon atoms. Thus, R² may be aliphatic or aromatic.When present, these lower carbon-number R² groups are preferably formedentirely of carbon and hydrogen, i.e., are hydrocarbon groups. Suchlower carbon-number R² groups preferably constitute less than 50% of theR₂ groups; however, when present, constitute about 1% to about 50%, andpreferably about 5% to about 35% of the total of the R² groups. Theidentity of R² at each occurrence is independent of the identity of R²at any other occurrence.

[0057] The —N(R^(3a))—R³—N(R^(3a))— group in formula (1) links twocarbonyl (C═O) groups. In a preferred embodiment of the invention, allof the R^(3a) groups in an ETPA gellant are hydrogen, so that R³ alonejoins the two nitrogen atoms shown in the formula—N(R^(2a))—R³—N(R^(3a))—. In this case, the R³ group contains at leasttwo carbon atoms, and optionally oxygen and/or nitrogen atoms, inaddition to any hydrogen atoms that are necessary to complete otherwiseunfilled valencies of the carbon, oxygen and nitrogen atoms. In apreferred embodiment, R³ is a hydrocarbon group, having 2 to about 36carbon atoms, preferably having 2 to about 12 carbon atoms, and morepreferably having 2 to about 8 carbon atoms. These carbon atoms may bearranged in a linear, branched or cyclic fashion, and unsaturation maybe present between any two of the carbon atoms. Thus, R³ may containaliphatic or aromatic structures. The identities of R³ and R^(3a) ateach occurrence are independent of their identities at any otheroccurrence.

[0058] The R³ groups may contain oxygen and/or nitrogen in addition tocarbon and hydrogen atoms. A typical oxygen atom-containing R³ group isa polyalkylene oxide, i.e., a group having alternating alkylene groupsand oxygen atoms. Indeed, the oxygenation in a R³ group is preferablypresent as an ether group. Representative polyalkylene oxides include,without limitation, polyethylene oxide, polypropylene oxide andcopolymers (either random, alternating or block) of ethylene oxide andpropylene oxide. Such oxygenated R³ groups are readily introduced intoan ETPA molecule of the invention through use of Jeffamine™ diamines(Huntsman Chemical, Inc., Houston, Tex.). These materials are availablein a wide range of molecular weights. While some of the R³ groups maycontain oxygen (at least about 1%), preferably a minor number (less than50%) of the R³ groups contain oxygen, and more preferably less thanabout 20% of the R³ groups contain oxygen. The presence ofoxygen-containing R³ groups tends to lower the softening point of theETPA.

[0059] When present, the nitrogen atoms in an R³ group are preferablypresent as secondary or tertiary amines. A typical nitrogenatom-containing R³ group having secondary amine groups is a polyalkyleneamine, i.e., a group containing alternating alkylene groups and aminegroups, which is sometimes referred to as a polyallylene polyamine. Thealkylene group is preferably a lower alkylene group, e.g., methylene,ethylene, (ie., —CH₂CH₂—), propylene etc. A typical polyallylene aminemay be represented by the formula —NH—(CH₂CH₂NH)_(m)CH₂CH₂—NH— wherein mis an integer from 1 to about 5.

[0060] However, the nitrogen atoms in the nitrogen-containing R³ groupmay alternatively (or additionally) be present as tertiary nitrogenatoms, e.g., they may be present in a heterocycle of the formula:

[0061] wherein R_(c) is a C₁₋₃ alkyl group.

[0062] In the above-described nitrogen atom-containing R³ groups, R^(3a)was hydrogen. However, R^(3a) is not limited to hydrogen. In fact,R^(3a) may be a C₁₋₁₀ alkyl group, preferably a C₁₋₅ alkyl group, andmore preferably a C₁₋₃ alkyl group. In addition, R³ and R^(3a), or twoR^(3a) groups, may together form a heterocyclic structure, e.g., apiperazine structure such as

[0063] In this case, the two R^(3a) groups may be seen as joiningtogether to form an ethylene bridge between the two nitrogen atoms,while R³ is also an ethylene bridge.

[0064] The ETPA gellant typically includes a mixture of ETPA moleculesof formula (1) in addition to, for example, by-products that are formedduring the ETPA-forming reaction. While the ETPA molecules of formula(1) may be purified from such by-products using, e.g., chromatography ordistillation, the by-products are typically either minimal in amount orimpart desirable properties to the gellant, and thus need not beseparated from the molecules of formula (1) in order for a suitable ETPAgellant to be formed.

[0065] This type of polyamide gellant is commercially available fromArizona Chemical Company as UniClear®. Examples of such commercial ETPAgellants which can be used as the polyamide gelling agent in thecomposition of the present invention are UniClear 80® (by ArizonaChemical company), UniClear 80V® (vegetable based UniClear 80® byArizona Chemical Company), UniClear 100® (by Arizona Chemical Company),and UniClear 100V® (vegetable based UniClear 100® by Arizona ChemicalCompany).

[0066] When UniClear 80® is used as the only polyamide gellant, theUniClear 80® typically totals from about 10 to about 90 weight % of thetotal composition. Preferably, the UniClear 80® totals from about 10 toabout 70 weight % of the total composition. More preferably, theUniClear 80® totals from about 20 to about 50 weight % of the totalcomposition.

[0067] A mixture of the fatty polyamides and ester terminated fattyacids may also be employed in the invention. In a polyamide gellantmixture, the fatty polyamide gellant is typically present in a weightratio of between about 1:11 to about 1:3, i.e., 1 part per weight fattypolyamide gellant to 11 parts total gellant to about 1 part per weightfatty polyamide gellant to 3 part per weight total gellant. Preferably,the fatty polyamide gellant is present in a part per weight ratio ofbetween about 1:10 to about 1:5, i.e., 1 part per weight fatty polyamidegellant to 10 part per weight total gellant to about 1 part per weightfatty polyamide gellant to 5 part per weight total gellant.

[0068] In a polyamide gellant mixture, the ETPA gellant is typicallypresent in a weight ratio of between about 2:3 to about 10:11, i.e., 2parts ETPA gellant to 3 parts total gellant to about 10 parts ETPAgellant to 11 parts total gellant. Preferably, the ETPA gellant ispresent in a weight ratio of between about 7:10 to about 5:6.

Solvent

[0069] The polyamide gellant is combined with a solvent in thecomposition of the invention to form a gel. The solvent is preferably alow polarity liquid that forms a gel upon being combined with a gellant.The solvents useful in the composition of the present invention can bedescribed generally as belonging to two classes. The first class ofsolvent is a fatty acid ester and the second class of solvent is ahydrocarbon oil.

[0070] A fatty acid ester is a fatty acid in which the terminalcarboxylic acid of the fatty acid is replaced by an ester. The fattyacid ester is thus primarily a hydrocarbon containing an esterfunctionality. Preferably, the fatty acid ester is a liquid having a lowpolarity. Such esters may be monofunctional esters (i.e. possessing asingle ester moiety) or they may be polyfunctional esters (i.e., havemore than one ester group).

[0071] The fatty acid ester solvents preferred for use in the inventioncan be further classified into four groups, hydrocarbyl fatty acidesters, monoalcohol fatty acid esters and polyol fatty acid esters,fatty acid ester alkoxylates, and sorbitol fatty acid esters.

[0072] The hydrocarbyl fatty acid esters are fatty acids containinghydrocarbon chains. These hydrocarbyl fatty acid esters are the reactionproducts of C1-C22 monocarboxylic acids with C1-C22 monoalcohols. Thehydrocarbyl fatty acid esters have a carbon chain length of at leastabout 9 carbons and preferably between about 9 to about 30 carbons. Thecarbon chain can be linear or branched and may be saturated orunsaturated. More preferably, the carbon chain length of these fattyacid esters is from between about 10 to about 28 carbons. Examplesinclude, but are not limited to, fatty acid esters such as isopropylisostearate, 2-ethylhexylstearate, 2-ethylhexylisostearate,2-ethylhexylpalmitate, stearic acid, isopropyl stearate, isopropylmyristate, isopropyl palmitate, and isostearyl benzoate. Preferred fattyacid esters of this type include those fatty acid esters in which the“fatty” portion of the fatty acid ester has a carbon chain length ofbetween about 10 to about 24 carbon atoms. Examples of preferred fattyacid ester solvents include 2-ethylhexylstearate, isopropyl stearate,isobutyl stearate, isopropylpalmitate, isobutylpalmitate,2-ethylhexylpalmitate, and 2-ethylhexylisostearate. More preferred fattyacid esters are those possessing a carbon chain length of between about16 to about 22 carbons. More preferred fatty acid ester solvents includemyristic acid, palmitic acid, and stearic acid.

[0073] Mixtures of this type of fatty acid ester solvent can also beused. The fatty acid ester can be mixed with another of the same type offatty acid ester or a different type of fatty acid ester. Examples of amixture of this type of fatty acid ester solvent include mixtures of2-ethylhexylstearate and 2-ethylhexylpalmitate and mixtures of2-ethylhexylisostearate and 2-ethylhexylpalmitate.

[0074] The monoalcohol fatty acid esters are fatty acid esters that aremade by reacting a monoalcohol (an alcohol having one alcoholfunctionality, a monofunctional alcohol) with a fatty acid. A propyleneglycol fatty acid ester is an example of a monoalcohol fatty acid esterpreferred for use in the invention. Examples include, but are notlimited to, propylene glycol myristate, propylene glycol caprilate,propylene glycol dicaprilate, propylene glycol laurate, propylene glycoldilaurate, propylene glycol isotearate, propylene glycol ricolinate, andpropylene glycol tetradecanoate. The propylene glycol fatty acid estersmore preferred for use in the invention are those in which the number ofcarbon atoms of the fatty acid is in the range of 10 to 22. Propyleneglycol myristate and propylene glycol tetradecanoate are more preferredpropylene glycol fatty acid esters.

[0075] The polyol fatty acid esters are made by reacting a polyol (analcohol having more than one alcohol functionality, a polyfunctionalalcohol) with a fatty acid. A glycol fatty acid ester is an example of apolyol fatty acid ester preferred for use in the invention. Examples ofglycerol fatty acid esters include glycerol dilaurate, glyceroltrioleate, glycerol monolaurate, glycerol stearate, glycerol isostearateand glycerol palmitate. The glycerol fatty acid esters more preferredfor use in the invention are those in which the number of carbon atomsof the fatty acid is in the range of 10 to 22.

[0076] The polyol fatty acid esters are made by reacting a polyol (analcohol having more than one alcohol functionality, a polyfunctionalalcohol) with a fatty acid. Preferred parent fatty acids are saturatedand unsaturated C10-C22 fatty acids. Preferred polyol fatty acid estersinclude glycerol fatty acid esters. Examples of glycerol fatty acidesters include glycerol dilaurate, glycerol trioleate, glycerolstearate, glycerol isostearate, glycerol palmitate, and glycerolmonolaurate. Preferred glycerol fatty acid esters include glyceroldilaurate, glycerol trioleate and glycerol monolaurate.

[0077] The fatty acid ester alkoxylates are made by reacting alkyleneoxides with fatty acids. Preferred parent fatty acids are saturated andunsaturated C12-C18 fatty acids. Examples include fatty acid esterethoxylates, fatty acid ester propoxylates, and fatty acid esterbutoxylates.

[0078] The sorbitol fatty acid esters are derivatives of sorbitan.Examples include sorbitan laurate, sorbitan trioleate, sorbitanpalmitate, sorbitan stearate, sorbitan tristearate, sorbitan oleate, andsorbitan sesquioleate. Preferred sorbitol fatty acid esters includesorbitan laurate and sorbitan trioleate. These sorbitan derivatives arecommercially available from ICI Americas, and are sold under thetrademarks SPAN® and ARLACEL®, with various alphanumeric designationsfor the different derivatives. The sorbitol fatty acid esters have theadded benefit of having emulsifying properties. Emulsifiers can improvethe solubility of various additives in the composition, such asfragrances or coloring agents, thereby improving the clarity of thecomposition when such additives are present.

[0079] Hydrocarbon oil can also be used as a solvent. The hydrocarboncan be saturated or unsaturated, aliphatic or aromatic, and linear,branched or cyclic. When the solvent is a hydrocarbon oil it functionsalso as a fuel to provide the flammable article with a substantialflame. If the flammable article is a translucent candle, the hydrocarbonoil serves to provide the candle with a robust and even flame. Thus, thehydrocarbon oil aids in the combustion process. The different types ofhydrocarbon oils that can be used in the invention include vegetableoil, animal oil and mineral oil.

[0080] Preferably, the hydrocarbon oil is mineral oil, also sometimesreferred to as medicinal oil. Mineral oil is a highly refined,colorless, tasteless and odorless petroleum oil (i.e., derived byprocessing petroleum/crude oil). Such mineral oils are highly refined inhaving substantially all volatile hydrocarbons removed therefrom, and inbeing hydrogenated (also called hydrotreated) in order to removesubstantially all unsaturation, e.g., aromatic groups have been reducedto the fully saturated analog. A preferred mineral oil to prepare a gelof the invention is so-called “white” mineral oil, which is water-white(i.e., colorless and transparent) and is generally recognized as safefor contact with human skin. Mineral oil may also be characterized interms of its viscosity, where light mineral oil is relatively lessviscous than heavy mineral oil. These terms are defined morespecifically in the U.S. Pharmacopoeia, 22nd revision, p. 899 (1990).

[0081] Any mineral oil may be used in the invention. The mineral oil canbe light mineral oil or heavy mineral oil. Light mineral oils arepreferred for use in the invention. Mineral oils are availablecommercially in both USP and NF grades. USP mineral oils haveviscosities that range from 35 cSt to 100cSt, and pour points that rangefrom −40° C to −12° C. NF light mineral oils have lower viscosities,typically 3-30 cSt, and pour points as low as −45° C. The mineral oilmay be of technical grade, having a viscosity ranging from 4-90 cSt anda pour point ranging from −12° C to 2° C. Examples of suitable,commercially available mineral oils include Sonneborn® and Carnation®white oils from Witco, Isopar® K and Isopar® H from Exxon, and Drakeol®and Peneteck® white mineral oils from Penreco.

[0082] The vegetable oil preferred for use in the invention istriglyceride oil. Examples of triglyceride oils include corn oil,soybean oil, peanut oil, sesame oil, sunflower oil, walnut oil,cottonseed oil, palm oil, rapeseed oil, and castor oil, etc. Castor oilis a preferred vegetable oil.

[0083] Other hydrocarbon oils that may be used as solvents in theinvention include relatively low molecular weight hydrocarbons includinglinear saturated hydrocarbons such as octane, nonane, decane, undecane,dodecane, tridecane, tetradecane, pentadecane, hexadecane, andoctadecane. Other relatively low molecular weight hydrocarbons includecyclic hydrocarbons such as decahydronapthalene (DECALIN), fuel gradehydrocarbons and branched chain hydrocarbons such as PERMETHYL fromPermethyl corporation and ISOPAR from Exxon Corp., including Isopar G,Isopar H, Isopar K, Isopar L, and Isopar M. Aromatic unsaturatedhydrocarbon oils can also be used in the invention, such as Hi-Sol 10and Hi-Sol 15 of Ashland. Hydrocarbon oil mixtures can also be used assolvents such as product PD-23 from Witco (Greenwich, Conn.).

[0084] The amount of hydrocarbon oil solvent in the composition involveconsiderations regarding the combustion and physical integrity andstability of the flammable article. The amount of hydrocarbon oilincluded in the composition will affect the size and intensity of theflame of the flammable article during combustion. In the situation wherethe flammable article is a candle, the type of wick employed in thecandle also factors into these considerations. The selection of anamount of hydrocarbon oil in the composition and the choice of wick maydepend upon the particular type of candle being manufactured. Too muchhydrocarbon oil may cause the phenomena of syneresis and sweating tooccur; in essence the oil will “bleed out” of the composition if it ispresent in the composition in too great an amount. Additionally, toolittle hydrocarbon oil may cause turbidity and reduce the clarity of thecomposition. Thus, an excessive amount of hydrocarbon oil stands toundermine the physical stability that is achieved by the combination ofsolvent, polyamide gellant and solubilizer.

[0085] In order to prepare a gel from the polyamide gellant and thefatty acid ester solvent, the two components are mixed together andheated until homogeneous. A temperature within the range of about80-150° C. is typically sufficient to allow the gellant to completelydissolve in the solvent. Upon cooling, the mixture forms a gel.

[0086] Although a “gel” is not easily defined, one skilled in the artreadily recognizes a “gel”. Generally, a gel is more viscous than aliquid or paste, and retains its shape when left undisturbed, i.e., isself-supporting. However, a gel is typically not as hard as a wax. Gelsmay be penetrated more easily than a wax-like solid, where “hard” gelsare relatively more resistant to penetration than “soft” gels. A rigidgel as defined herein resists deformation upon the application of aforce.

[0087] Almdale et al. (Polymer Gels and Networks, Vol. 1, No. 5 (1993))list two criteria for defining a system as a gel: (1) a gel consists oftwo or more components, one of which is a liquid, present in substantialquantities, and (2) a gel is a soft material which is solid orsolid-like. Thus, the composition of the present invention from whichthe flammable article is made, with all of the components in addition tothe polyamide gellant and the fatty acid ester solvent, meets thisdefinition and can be considered to be a gel.

[0088] Additional Components

[0089] One or more plasticizers may be added to the composition of thepresent invention. When present, the plasticizers total about 0-15% byweight of the composition, preferably about 7-12% by weight of thecomposition. A plasticizer is an organic compound added to a polymerboth to facilitate processing and to increase the flexibility anddurability of the final product by internal modification (salvation) ofthe polymer molecule. The polymer molecule is held together by secondaryvalence bonds such as hydrogen bonding, dipole-dipole interactions, andVan Der Waals interactions. The plasticizer replaces some of theseinteractions with plasticizer to polymer bonds, thus aiding movement ofthe polymer chain segments. Examples of common plasticizers includenonvolatile organic liquids and low melting solids (such as phthalate,adipate, and sebacate esters), polyols such as ethylene glycol and itsderivatives, tricesyl phosphate, castor oil, etc.

[0090] Thus, plasticizers function in the present invention to increasethe structural flexibility of the composition, allowing the compositionto alter its shape instead of cracking or splitting in response to thethermal stresses associated with the burning process. Phthalate estersare preferred for use as plasticizers in the invention. Examplesinclude, but are not limited to, dioctylphthalate, dibutylphthalate,bis(2-ethylhexyl)terephthalate, bis(2-ethylhexyl)adipate, andtris(2-ethylhexyl)trimelltate. Suitable plasticizers also includemixtures of these plasticizers. A mixture of dioctylphthalate anddibutylphthalate is a preferred mixture of plasticizers.

[0091] The composition of the present invention may also contain one ormore fragrances. The fragrances may be those fragrances suitable for usein candles; such type of fragrances will be well known to those ofordinary skill in the art. Examples of such fragrances include, but arenot limited to, Citronella AN114351 Sweet Peach, AN 114349 MountainBerry, AN 114350 Country Garden, AN 114462 Lavender Meadows, AN 114463Strawberries 'N Cream and AN 114215 Vanilla from Noville Corp., SouthHackensack, N.J. The amount of fragrance which should be present in thecomposition will depend on the intensity of the fragrance and the degreeto which it is desired that the composition emit fragrance. This amountcan be readily determined by the artisan of ordinary skill, with littleor no experimentation.

[0092] The compositions of the present invention may also contain acoloring agent, which produces a desired color appearance. A compositionhaving a coloring agent would preferably be translucent and wouldprovide clear color without adding any haziness or cloudiness to thecomposition. The coloring agents may be those coloring agents suitablefor use in candles; such type of coloring agents will be well known tothose of ordinary skill in the art. The coloring agent may, for example,be a pigment or a dye, however, a dye is preferred for providing color,especially oil soluble dyes. Oil soluble dyes are well known in the art,and may be obtained from, for example, Pylam Products, Tempe Ariz.Examples of such dyes include, but are not limited to, D&C violet #2,D&C yellow #11, D&C green #6, and D&C red #17.

[0093] In the preferred embodiment of a candle, a translucent candlemade from the composition preferably has a burn rate of around 4-6 gramsper hour, similar to a wax candle. This burn rate differs from the burnrate typically seen with a styrene/rubber translucent or clear candle,which has a significantly slower burn rate of around 2 grams per hour.Exemplary candles made from the composition of the present inventioninclude candles with dimensions measuring 2 inches in diameter and 4inches tall, candles that are 3 inches in diameter and either 3 incheshigh or 6 inches high.

[0094] Preferably, the flammable article burns without darkening oremitting black smoke. It is also preferable that a flammable articlemade from the composition of the present invention maintains itsstructural integrity during storage or when burning. In the preferredembodiment of a candle, the candle does not crack or split, nor exhibitsweating or syneresis, nor do the sides of the candle bulge out orexperience discoloration in the form of the formation of opaque regionsduring burning or storage. Furthermore, it is preferred that theflammable article does not superheat and the sides of the candle remaincool to the touch when the article is burning, allowing the article tobe handled while burning. It is also preferable that the compositionfrom which the flammable article is made is thermoreversible, that is,after the article has finished burning the molten pool of thecomposition solidifies and the composition does not experience asignificant change in its properties. The flammable article preferablyhas a high degree of clarity with minimal to no haziness, cloudiness oropaqueness. More preferably, the flammable article is what could bedescribed as crystal clear. This crystal clarity should remain even whenadditives such as fragrance or coloring agents are added.

[0095] Specifically, a candle which has been shown to exhibit minimal tono syneresis or sweating when stored for six months at 30° C. is acomposition comprising the following weight percents: 50 wt % UniClear80®, 10 wt % 2-ethylhexylstearate, 5 wt % isostearic acid, and 35 wt %mineral oil. An example of another preferred embodiment of the inventionthat exhibits the properties described above is a candle comprisingabout 2-10% by weight polyamide gellant; about 20-50% by weight of esterterminated polyamide gellant; about 15-30% by weight of mineral oil;about 10-20% by weight of fatty acid ester, said fatty acid estercomprising a branched carbon chain of between about 10 to about 28carbons; about 2-10% by weight of isostearic acid; about 0-10% by weightof isostearyl alcohol; about 2-15% by weight of plasticizer; about 1-4%by weight of fragrance; about 1-4% by weight of coloring agent; and awick. Yet another example of another preferred embodiment of theinvention that exhibits the preferred properties described above is acandle comprising about 10-30% by weight polyamide gellant; about 10-70%by weight of ester terminated polyamide gellant; about 10-30% by weightof mineral oil; about 15-50% by weight of fatty acid ester, said fattyacid ester comprising a branched carbon chain of between about 10 toabout 28 carbons; about 5-15% by weight of isostearic acid; about 0-10%by weight of isostearyl alcohol; about 10-75% by weight of plasticizer;about 0-5% by weight of fragrance; about 0-5% by weight of coloringagents; and a wick.

[0096] The wicks employed in the candle are those wicks typically usedwith translucent or transparent candles. Candle wicks are commerciallyavailable and the wick is selected in consideration of the size of thecandle. Preferred wicks are made from uniform, tear-resistant cottonyarn made of medium and long-stapled cotton which is seasoned and doesnot have moisture damage. A typical wick has from 15-45 strands (plys).Preferably, the wick has from 30 to 43 plys. Examples of preferred wicksinclude, but are not limited to, 31 ply cotton wicks possessing anapproximate burning time of 40 hours, 43 ply cotton with an approximateburning time of 60 hours, and 43 ply cotton with an approximate burningtime of 120 hours. A transparent wick may be used so that the entirecandle may be transparent. Preferably, the wick does not leave ashesupon burning and burns without visible release of soot. Preferably, thewick has an upright posture upon exiting the candle, with a slightcurvature and formation of a glow point at the wick tip upon burning.The selection of an appropriate wick for a given translucent candle isreadily made by one of ordinary skill in the art.

[0097] The flammable article is generally made by mixing together thepolyamide gellant and the fatty acid ester solvent and heating until themixture is homogeneous. The solubilizer in the composition is added tothe mixture at a suitable temperature to assist in achieving ahomogeneous mixture. A temperature within the range of about 80-150° C.is typically sufficient to allow the gellant to completely dissolve inthe solvent. Upon cooling, the mixture forms the composition of theinvention. A flammable article may be made from the composition byemploying a suitable mold. For example, a candle can be made from thesolid composition by employing a mold with a steel bar to provide forthe placement of the wick. It is an advantage of the present inventionthat once cooled, the flammable article can be readily removed from themold without defacing the surface of the article or experiencing thedifficulty with demolding experienced by the prior art.

[0098] The invention will now be described in detail with respect toshowing how certain specific representative embodiments thereof will bemade, the materials, apparatus and process steps being understood asexamples that are intended to be illustrative only. Thus, it isunderstood that the examples are merely illustrative and the inventionis not intended to be limited by them.

EXAMPLES Example 1

[0099] Transparent candles representative of the present invention wereprepared as follows:

[0100] (1) 2-ethylhexylstearate(2-EHS) was added into a steel container,which was stirred and heated to a temperature of 110° C.

[0101] (2) The gellant Versamid 1655® was added little by little, whilethe content of this container was heated to about 94-96° C. and stirred.During the addition of gellant, isostearic acid was added to obtain ahomogeneous solution.

[0102] (3) The composition, totaling 1 kg in weight, was poured into amold, which has a steel bar in the center. The composition was allowedto cool to room temperature and solidify. The steel bar was removed. Awick was then threaded through the hole in the composition left by thesteel bar.

Example 2

[0103] Further transparent candles representative of the presentinvention were prepared as follows:

[0104] (1) 2-ethylhexylstearate(2-EHS) was added into a steel container,which was stirred and heated to a temperature of 110° C.

[0105] (2) The gellant UniClear 80® was added little by little, whilethe content of this container was heated to around 94-96° C. andstirred. While the temperature of the composition was around 90° C. andduring the addition of gellant, isostearic acid was added to obtain ahomogeneous solution.

[0106] (3) The composition, totaling 1 kg in weight, was poured into amold, possessing a steel bar in the center. The composition was allowedto cool to room temperature and solidify. The steel bar was removed. Awick was then threaded through the hole in the composition left by thesteel bar.

Example 3

[0107] General Procedure for Preparation of Compositions of Table 1

[0108] (1) The solvent was added into a container which was agitated andheated to a temperature of 110° C.

[0109] (2) The gellant UniClear 80® was added gradually to thecontainer, while the content of this container was heated to atemperature of around 95-100° C. While the gellant was being added andwhen the temperature of the container was around 90° C., Isostearic acidwas added to obtain a homogeneous solution.

[0110] (3) The remaining components were added individually in an orderdetermined by the amount of the component in the composition, with thelargest amount being added first. Thus, the fragrance and coloring agentwere added last.

[0111] (4) The composition was poured into a mold possessing a steel barin the center. The composition was allowed to cool to room temperatureand solidify. The steel bar was removed. The wick was threaded throughthe hole left by the steel bar.

[0112] Using the above procedure, the compositions listed in Table 1were prepared. The units of Table 1 are weight %. TABLE 1 Composition 12 3 4 5 6 7 8 9 2-EHS 20 15 20 25 40 50 45 2-EHP 65 Gellant 1 40 12 1655Gellant 2 5 2620 Gellant 3 3 2626 Gallant 4 27 40 35 32 35 35 20 10UniClear 80 Isostearyl 5 7 5 8 5 5 alcohol Isostearic 5 5 10 5 10 5 5acid Plasticizer 10 10 75 Mineral Oil 13 30 30 10 10 10 10 10

Example 4

[0113] Transparency Measurements

[0114] A sample cut in a thickness of 1 cm was placed on printedcharacters of 12 points to examine if they can be identified through thesample.

[0115] The evaluation is as follows: ◯, clearly identified; Δ, barelyidentified; and ×, unidentified.

[0116] Each of compositions 1 through 10 in Example 3 was evaluatedusing this method. Composition Transparency 1 Δ 2 ∘ 3 ∘ 4 ∘ 5 ∘ 6 ∘ 7 ∘8 ∘ 9 ∘ 10 ∘

What is claimed is:
 1. A flammable article comprising: (i) a polyamidegellant, selected from the group consisting of fatty polyamides andester terminated polyamides; (ii) a fatty acid ester solvent having acarbon chain length of at least about 9 carbons; and (iii) a fatty acidsolubilizer, said solubilizer comprising at least 1% by weight of theflammable article.
 2. The flammable article of claim 1 furthercomprising a fatty acid solubilizer having a carbon chain of betweenabout 1 to about 22 carbons.
 3. The flammable article of claim 1 furthercomprising a fatty alcohol solubilizer having a branched carbon chain ofbetween about 10 to about 20 carbons.
 4. The flammable article of claim1 wherein the solubilizer comprises isostearic acid, said flammablearticle further comprising isostearic alcohol.
 5. The flammable articleof claim 1 wherein the solubilizer comprises isostearic acid.
 6. Theflammable article of claim 1 wherein said polyamide gellant comprises amixture of fatty polyamide and ester terminated polyamide.
 7. Theflammable article of claim 6 wherein the fatty polyamide is present in aweight ratio of parts fatty polyamide to parts polyamide gellant ofbetween about 1:11 to about 1:3.
 8. The flammable article of claim 6wherein the fatty polyamide is present in a weight ratio of parts fattypolyamide to parts polyamide gellant of between about 1:10 to about 1:5.9. The flammable article of claim 6 wherein the ester terminatedpolyamide is present in a weight ratio of parts ester terminatedpolyamide to parts polyamide gellant of between about 2:3 to about10:11.
 10. The flammable article of claim 6 wherein the ester terminatedpolyamide is present in a weight ratio of parts ester terminatedpolyamide to parts polyamide gellant of between about 7:10 to about 5:6.11. The flammable article of claim 1 wherein the fatty acid ester has abranched carbon chain of between about 16 to about 22 carbons.
 12. Theflammable article of claim 1 wherein the fatty acid ester is selectedfrom the group consisting of 2-ethylhexylstearate, isopropyl myristate,2-ethylhexylpalmitate, 2-ethylhexylisostearate, and isopropyl stearate.13. The flammable article of claim 1 wherein the fatty acid estercomprises a sorbitol fatty acid ester, a monoalcohol fatty acid ester, apolyol fatty acid ester, a fatty acid ester alkoxylate, or hydrocarbylfatty acid ester.
 14. The flammable article of claim 13 wherein themonoalcohol fatty acid ester is a propylene glycol fatty acid ester. 15.The flammable article of claim 13 wherein the polyol fatty acid ester isa glycerol fatty acid ester.
 16. The flammable article of claim 13wherein the fatty acid ester alkoxylate comprises fatty acid esterethoxylate, fatty acid ester propoxylate, or fatty acid esterbutoxylate.
 17. The flammable article of claim 1 further comprisinghydrocarbon oil.
 18. The flammable article of claim 17 wherein thehydrocarbon oil comprises light mineral oil.
 19. The flammable articleof claim 17 wherein the hydrocarbon oil comprises vegetable oil.
 20. Theflammable article of claim 17 wherein the hydrocarbon oil comprisescastor oil.
 21. The flammable article of claim 1 wherein the flammablearticle is a candle.
 22. The flammable article of claim 1 wherein saidpolyamide gellant comprises between about 10 to about 90% by weight ofthe article, said fatty acid ester comprises between about 5 to about70% by weight of the article, and said solubilizer comprises betweenabout 1 to about 75% by weight of the article.
 23. The flammable articleof claim 1 wherein said polyamide gellant comprises between about 10 toabout 70 weight % of the article, said fatty acid ester comprisesbetween about 10 to about 50 weight % of the article, and saidsolubilizer comprises between about 2 to about 30 weight % of thearticle.
 24. The flammable article of claim 1 wherein said polyamidegellant comprises between about 40 to about 60 weight % of the article,said fatty acid ester comprises between about 10 to about 20 weight % ofthe article, and said solubilizer comprises between about 3 to about 10weight % of the article.
 25. The flammable article of claim 1 furthercomprising one or more plasticizers.
 26. The flammable article of claim24 wherein the plasticizers comprise between about 0-15% by weight ofthe article.
 27. The flammable article of claim 24 wherein theplasticizers are selected from the group consisting of dioctylphthalate,dibutylphthalate, bis(2-ethylhexylterephthalate),bis(2-ethylhexyl)adipate, and tris(2-ethylhexyl)trimelltate.
 28. Theflammable article of claim 1 further comprising one or more fragrances.29. The flammable article of claim 1 further comprising one or morecoloring agents.
 30. The flammable article of claim 28 furthercomprising one or more coloring agents.
 31. A translucent solid candle,comprising: about 10-30% by weight fatty polyamide; about 10-70% byweight of ester terminated polyamide; about 10-30% by weight of mineraloil; about 15-50% by weight of fatty acid ester, said fatty estercomprising a branched carbon chain of between about 10 to about 24carbons; about 5-15% by weight of isostearic acid; about 0-10% by weightof isostearyl alcohol; about 10-75% by weight of plasticizer; about 0-5%by weight of fragrance; about 0-5% by weight of coloring agents; and awick.
 32. The candle of claim 31 wherein the fatty acid ester isselected from the group consisting of 2-ethylhexylstearate andethylhexylpalmitate.
 33. The candle of claim 31 wherein the fatty acidester comprises a mixture of 2-ethylhexylstearate andethylhexylpalmitate.
 34. The candle of claim 31 wherein the esterterminated polyamide comprises UniClear 80®.
 35. The candle of claim 31wherein the plasticizer is selected from the group consisting ofdioctylphthalate and dibutylphthalate.
 36. The candle of claim 31wherein the plasticizer comprises a mixture of dioctylphthalate anddibutylphthalate.
 37. A translucent solid candle, comprising: about2-10% by weight fatty polyamide; about 20-50% by weight of esterterminated polyamide; about 15-30% by weight of mineral oil; about10-20% by weight of fatty acid ester, said fatty ester comprising abranched carbon chain of between about 10 to about 24 carbons; about2-10% by weight of isostearic acid; about 0-10% by weight of isostearylalcohol; about 2-15% by weight of plasticizer; about 1-4% by weight offragrance; about 1-4% by weight of coloring agent; and a wick.
 38. Thecandle of claim 37 wherein the fatty acid ester is selected from thegroup consisting of 2-ethylhexylstearate and ethylhexylpalmitate. 39.The candle of claim 37 wherein the fatty acid ester comprises a mixtureof 2-ethylhexylstearate and ethylhexylpalmitate.
 40. The candle of claim37 wherein the plasticizer is selected from the group consisting ofdioctylphthalate and dibutylphthalate.
 41. The candle of claim 37wherein the plasticizer comprises a mixture of dioctylphthalate anddibutylphthalate.
 42. A translucent solid candle, comprising: about40-60% by weight UniClear 80®; about 5-20% by weight of fatty acidester, said fatty ester comprising a branched carbon chain of betweenabout 16 to about 22 carbons; about 30-40% by weight of mineral oil;about 2-10% by weight of isostearic acid; about 5-15% by weight2-ethylhexylstearate; and a wick.